Impact of nitrogen and phosphorus additions on soil gross nitrogen transformations in a temperate desert steppe

Nutrient addition has a significant impact on plant growth and nutrient cycling. Yet, the understanding of how the addition of nitrogen (N) or phosphorus (P) significantly affects soil gross N transformations and N availability in temperate desert steppes is still limited. Therefore, a ¹⁵N tracing experiment was conducted to study these processes and their underlying mechanism in a desert steppe soil that had been supplemented with N and P for 4 years in northwestern China. Soil N mineralization was increased significantly by P addition, and N and P additions significantly promoted soil autotrophic nitrification, rather than NH₄⁺-N immobilization. The addition of N promoted dissimilatory NO₃⁻ reduction to NH₄⁺, while that of P inhibited it. Soil NO₃⁻-N production was greatly increased by N added alone and by that of N and P combined, while net NH₄⁺-N production was decreased by these treatments. Soil N mineralization was primarily mediated by pH, P content or organic carbon, while soil NH₄⁺-N content regulated autotrophic nitrification mainly, and this process was mainly controlled by ammonia-oxidizing bacteria rather than archaea and comammox. NH₄⁺-N immobilization was mainly affected by functional microorganisms, the abundance of narG gene and comammox Ntsp-amoA. In conclusion, gross N transformations in the temperate desert steppe largely depended on soil inorganic N, P contents and related functional microorganisms. Soil acidification plays a more key role in N mineralization than other environmental factors or functional microorganisms.     

Immunoblotting, ELISA and culture evidence for Chlamydiaceae in sows on 258 Belgian farms

The prevalence of Chlamydiaceae infections on 258 closed pig breeding farms in Belgium was examined. For this purpose, 258 farms were randomly selected in the provinces West-Vlaanderen (44%), Oost-Vlaanderen (20%), Antwerpen (10%) and Vlaams-Brabant (6%). Of all farms examined, 96.5% were positive for Chlamydia-specific antibodies in ELISA and most were moderately to strongly positive. ELISA results revealed only 9 (3.5%) sero-negative farms. None of the ELISA negative sera reacted in immunoblotting. Only 212 of 249 ELISA positive sera reacted positive in immunoblotting. Additionally, 23 autopsy samples were examined by isolation in Vero cells. The major outer membrane sequence of the one isolate obtained showed 98.6% amino acid homology to the one of Chlamydophila psittaci strain CP3, formerly isolated from a pigeon. Present observations indicate that chlamydial infections are nearly endemic in the Belgian pig population and that Belgian pigs can become infected with C. psittaci. Nevertheless, the role and significance of Chlamydiaceae as pathogens in pigs remain unsolved and require further investigation.     

Characterization of turkey coronavirus from turkey poults with acute enteritis.

The present study was to characterize turkey coronavirus associated with turkey poult enteritis and mortality. Intestinal contents or intestines from affected turkey poults and inoculated turkey embryos contained coronaviruses as revealed by electron microscopy or were positive for turkey coronavirus by immunofluorescent antibody assay. Sucrose density gradient ultracentrifugation of the virus-containing intestinal homogenate yielded two opalescent bands corresponding to the buoyant densities of 1.14-1.15 and 1.18-1.20 g/ml, respectively. Coronaviral particles from intestinal contents or the sucrose density gradient preparation were mainly spherical in shape and had envelope and central depression. They were surrounded by a fringe of regularly spaced petal-shaped projections attached to the particles by a short stalk. Purified viruses hemagglutinated rabbit erythrocytes with a titer of 16. Major protein bands of purified viruses analyzed by SDS-PAGE were located at 200, 100-110, 50-60, and 30-35 kDa. The patterns of protein bands were consistent with those of Minnesota or Quebec turkey coronavirus isolates. A 568 bp nucleotide fragment of turkey coronavirus spike protein gene was amplified from RNA of inoculated turkey embryo intestine or purified virus. Sequence analysis of the 568 bp PCR product revealed high degree of identity with the corresponding spike protein gene sequence of human and bovine coronaviruses. The results indicated that turkey coronavirus was associated with turkey poults with acute enteritis.     

Distribution of preservatives in thermally modified Scots pine and Norway spruce sapwood

Studying the impregnation and distribution of oil-based preservative in dried wood is complicated as wood is a nonhomogeneous, hygroscopic and porous material, and especially of anisotropic nature. However, this study is important since it has influence on the durability of wood. To enhance the durability of thermally modified wood, a new method for preservative impregnation is introduced, avoiding the need for external pressure or vacuum. This article presents a study on preservative distribution in thermally treated Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) sapwood using computed tomography scanning, light microscopy, and scanning electron microscopy. Secondary treatment of thermally modified wood was performed on a laboratory scale by impregnation with two types of preservatives, viz. Elit Träskydd (Beckers) and pine tar (tar), to evaluate their distribution in the wood cells. Preservative solutions were impregnated in the wood using a simple and effective method. Samples were preheated to 170 °C in a drying oven and immediately submerged in preservative solutions for simultaneous impregnation and cooling. Tar penetration was found higher than Beckers, and their distribution decreased with increasing sample length. Owing to some anatomical properties, uptake of preservatives was low in spruce. Besides, dry-induced interstitial spaces, which are proven important flow paths for seasoned wood, were not observed in this species.     

Measures of self-efficacy and norms for low-fat milk consumption are reliable and related to beverage consumption among 5th graders at school lunch

OBJECTIVE: To determine the reliability and validity of scales measuring low-fat milk consumption self-efficacy and norms during school lunch among a cohort of 5th graders. DESIGN: Two hundred and seventy-five students completed lunch food records and a psychosocial questionnaire measuring self-efficacy and norms for school lunch low-fat milk consumption during the fall and spring semesters of the 1998-1999 academic year. Test-retest reliability was assessed in participants who also completed the questionnaire in the spring semester (n = 262). Principal component analyses identified and confirmatory factor analyses confirmed latent variables. Bivariate correlations measured construct validity. SETTING: Houston-area middle school. SUBJECTS: Fifth graders (n = 275) from one middle school in southeast Texas. RESULTS: Two scales measuring psychosocial influences of low-fat milk consumption were identified and proved reliable in this population: milk self-efficacy and milk norms. Milk self-efficacy and norms were positively correlated with milk consumption and negatively correlated with consumption of sweetened beverages. CONCLUSIONS: These questionnaires can be used in similar interventions to measure the impact of self-efficacy and norms for drinking low-fat milk during school lunch.     

Safety evaluation of an oak-flavored milk powder containing ellagitannins upon oral administration in the rat

Ellagitannins are phenolic compounds that occur in a number of dietary sources such as walnuts, raspberries, pomegranate, strawberries, and oak-aged wines. Ellagitannins have been acknowledged to have antioxidant and cancer chemopreventive activities. However, ellagitannins have also been considered to be "antinutrients" and have been reported to provoke adverse effects in animals. In this context, risk assessment studies are demanded to ensure that chemicals present in food do not compromise food safety. Oak-flavored milk can be obtained by thermal treatment of milk in the presence of oak shavings. The oak-flavored milk can be used to impart wood-like flavor to different recipes. The present study evaluated, under a subchronic approach, the safety of an oak-flavored milk powder containing ellagitannins in rats upon repeated oral administration for 96 days. The effect of 30% oak-flavored milk powder in the diet was evaluated. This amount involved a margin of safety equivalent to the daily intake of 134 yogurts by a 70 kg person for 96 days. Growth rate, food utility index, 9 hematological, and 13 serobiochemical parameters as well as the metabolism and tissue distribution of ellagitannins and derived metabolites were studied. Overall, no significant differences were found in oak-milk-fed rats in any blood parameter analyzed. No effect was found on growth rate and food utility index. Urolithin A was identified in feces of rats fed oak-flavored milk and the glucuronide derivative in urine. No metabolites were found in the liver, kidney, or uterus. Histopathological analysis of liver and kidney corroborated the absence of toxicity. Therefore, these results suggest that the intake of the oak-flavored milk powder assayed in this study is safe and does not involve potential hazard to human health.     

Ultraviolet-C and induced stilbenes control ochratoxigenic Aspergillus in grapes

This study investigated the efficacy of ultraviolet-C (254 nm) and induced stilbenes to inhibit Aspergillus carbonarius and Aspergillus tubingensis and control ochratoxin A production in grapes. In addition, the stilbene synthesis as a response to UV-C treatment and to infection of ochratoxigenic Aspergillus was compared. The initial microbial inactivation by a previously optimized UV-C illumination protocol for increasing trans-resveratrol content in grapes (50 W/m (2), 40 cm, 60 s) was similar on undamaged and damaged grapes, achieving 1.2 and 1.3 log conidia/100 g reductions, respectively. After 5 days of storage at 22 degrees C, UV-C treatment and the stilbenes induced by UV-C inhibited ochratoxigenic Aspergillus growth in undamaged grapes. UV-C elicited the biosynthesis of trans-resveratrol, while microbial infection and tissue damage triggered the biosynthesis of trans-piceid. trans-Resveratrol was not synthesized as a consequence of ochratoxigenic Aspergillus contamination. However, when trans-resveratrol was synthesized by UV-C, it contributed to inhibiting the development of ochratoxin A producing aspergilli. Furthermore, UV-C treatment also contributed to decrease ochratoxin A production by ochratoxigenic aspergilli. Therefore, UV-C is a promising emerging technology either for reducing the potential ochratoxigenic risk in grapes, which is of particular interest to the wine industry, and also for increasing trans-resveratrol content of grapes, which would provide an added value to the wine.     

Otolith elemental characteristics of whitefish (Coregonus lavaretus) from brackish waters of the Gulf of Bothnia,Baltic Sea

To investigate whether European whitefish (Coregonus lavaretus) groups in the brackish (≤7%) Gulf of Bothnia (Baltic Sea) express specific otolith elemental characteristics, concentrations of elements (Ca, Ba, Sr, Zn, Mn, Fe) in whole otoliths were studied by inductively coupled plasma‐optical emission spectrometry. Whitefish (N = 67) were sampled from six different latitudinal sites; four in the sea and two in rivers along the west coast of Finland, and from a fresh water lake for comparison. The concentration of several elements showed significant differences among sampling sites. Otolith Ba concentrations were higher at the northern sampling sites compared to the southern ones, thereby showing negative association to capture‐habitat salinity. In contrast, otolith Sr and Zn concentrations were lower at the northern sampling sites, thereby associating positively to capture‐habitat salinity. Otolith Mn concentrations did not associate with latitude or salinity but markedly varied between sampling sites. Elevated Fe concentrations occurred in fish otoliths from the two northernmost sites. Ca concentrations were at the same levels in otoliths from all whitefish samples. Otoliths of whitefish from the lake had very high Ba and low Sr concentrations compared to concentrations in otoliths from whitefish in the sea and rivers. Our results show that otolith elemental characteristics of whitefish vary considerably at various geographic scales showing high potential for population identification using elemental fingerprints. Analysis of otolith elemental characteristics may therefore provide an efficient tool for the identification of main areas of residence, spawning locations, and migration routes, thus contributing towards the sustainable management of whitefish stocks.